01 - Software Quality

8/12/2019 01 - Software Quality

1/23

SOFTWARE QUALITY


2/23

CHOOSE A CELLPHONENokia 7210 MyPhone T52

P5, 500 P5, 200


3/23

COMPARISON

Nokia 7210 MyPhone T52

Weight 69.8g 81g

Size 10 x 45 x 10.6mm 10 x 47 x 14 mm Features

Music player Yes Yes

Memory 2GB Transflash

FM Radio Yes Yes


4/23

Group Discussion

Which cellphone would you choose?

Why?


5/23

History of Quality Started with craftsmen building unions or guilds in late

13thcentury

Rise of the factory system started in UK in 1750s andgrew during Industrial Revolution in mid 1750s World War II - quality became an important component Quality Revolution in Japan with inputs from

Americans Joseph Juran and W. Edwards Deming

1970s high quality Japanese products in Americanmarket

TQM (Total Quality Management) as a response


6/23

What is Quality?

Five Different Quality Views (David Garin)

Transcendental something that can berecognized but not defined

User fitness for purpose

Manufacturing conformance to specifications

Product inherent characteristics of the product Value dependent on the amount a customer iswilling to pay for it


7/23

What is Quality?

The degree to which a system, component, orprocess meets (1) specified requirements, and(2) customer or user needs or expectations

(IEEE Standard Glossary of Software Engineering Terminoloy)


8/23

Nature of Quality

Myths

Quality is defined by the producer, not thecustomer

Quality relates only to the final product

Software development is the biggest contributor todefects

Improving quality always costs more money

Quality is the responsibility of the QualityAssurance Department


9/23

Nature of Quality

Real Story The customer (user) defines quality

Quality is determined by every process, supportfunction and subproduct

Software defects are traceable to the reqts as amajor contributor, and can occur during any life

cycle phases Improving quality will result in a lower life cycle

cost Quality is everyones job, on every task they

perform


10/23

Why Quality?

"Quality is free. Its not a gift, but its free. Theunquality things are what cost money." --

Philip B. Crosby


11/23

Why Quality?

Productivity and Economic

IT spending is expected to hit $2 trillion in 2013

(Gartner) IT has contributed approx $50 billion in productivity

output (Information Week)

IT errors can also contribute to loss, estimated at $60

billion annually in economic losses


12/23

Why is There a Cost to SoftwareQuality?

Rooted in the requirement to assure that thedeveloped product meets the approvedspecifications


13/23

Why is There a Cost to SoftwareQuality? Nature and size of investment determined by:

Requirements imposed by the buyer

Kind of technologies used

Kind of product being developed

Internal development environment

Project budget Degree of incorporating repeatable processes and

measures in everyday practices

Domain knowledge possessed by development


14/23

What is Software Quality?

composite of all attributes which describe thedegree of excellence of the computer system

(Fisher and Light)

the degree to which a software productpossesses a specified set of attributes necessary

to fulfill a stated purpose (Donald Reifer) Software quality is the fitness for use ofthe software product


15/23

Software Quality Assurance planned and systematic pattern of all actions

necessary to provide adequate confidence that

an item or product conforms to establishedtechnical requirements

What does this mean?

Provide an independent review of developmentprocess (products and process)

Check for conformance to standards Reduce the costs of correcting defects


16/23

Software Quality Control

independent evaluation of the ability of thesoftware process to produce a usable software

product


17/23

Software Maintainability 60 to 70% of software expense allocated to

maintenance

(1) use of conducting scheduled inspections andservicing, called serviceability, and (2) case ofrestoring service after failure called repairability(JM Juran)

Perspective on maintainability:

Corrective correction of faults uncovered in aprogram Adaptive response to a change in the programs

operating circumstances Perfective enhancements of all kinds


18/23

Software Maintanability

process of modifying a software system orcomponent after delivery to correct faults,improve performance or other attribute, or

adapt to a changed environment


19/23

Verification and Validation

Verification

process of evaluating a system to determine

whether the products of a given developmentphase satisfy the conditions imposed at the start ofthe phase (IEEE Standard Glossary)

Validation

process of evaluating a system to determinewhether it satisfies specified requirements (IEEE

Standard Glossary)


20/23


21/23

Test and Evaluation (T&E) Testing - process of operating a system or system

component under specified conditions, observing

or recording the results, and making an evaluationof some aspect of the system or component (IEEE)

Evaluation to appraise, to judge the quality orworth of

Testing and Evaluation:process of exercising complete programs to judge

their quality through the fulfillment of specifiedrequirements


22/23

Whats the Difference?

Testing and Evaluation vs Verification andValidation

V &V can be accomplished without testing thesoftware (but usually is not)

V &V traceability of requirements

Verification accomplished through tracing ofrequirements embodied in the design specificationsand code

Validation accomplished through test closuretraceability


23/23

Software Process Improvement

deliberate, planned methodology followingstandardized documentation practices to capture

on paper (and in practice) the activities,methods, practices and the associated products.As each activity, method practice andtransformation is documented, each is analyzedagainst the standard of value added to theorganization

Documents

01 - Software Quality